if its not crowbaring the power supply it will be fine, as far as protection you want to throw a diode across the solenoid ( cathode to + side, anode to - side) so it wont spit out back EMF on your power lines causing spikes and noise

otherwise your arduino's voltage regulator might run a little warm, but it should be fine as it has protection in the IC

if its not crowbaring the power supply it will be fine, as far as protection you want to throw a diode across the solenoid ( cathode to + side, anode to - side) so it wont spit out back EMF on your power lines causing spikes and noise

Thanks for the info - any ideas on the spec of the diode? or maybe a part # for me to look into?

Thanks for the info - any ideas on the spec of the diode? or maybe a part # for me to look into?

just your standard black 4000 series power/rectifier diode, its not going to carry load, its just going to provide a short when the electromagnetic field collapses and sends a 100v + pulse back down the line.

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Not sure if I need it since I am unsure if this is better than the simple Voltage Regulator on the arduino?

Would it be worth putting this inline?

oh its better cause its not burning off the extra voltage as heat, and if its worth it or not depends on how much current is demanded of the on board regulator and how hot its getting.

the basic rule is stick your finger on it, and if you can hold it there for 5 seconds or more its not too hot. The datasheet says max 150c junction temperature (the chip itself, not the case) with a 15c per watt junction to case difference ...if you wanted to run the maths and figure it all